Current Dependent Current Sources -- F Elements

Current Controlled Current Source (CCCS)

The syntax is:

Linear

Fxxx n+ n- <CCCS> vn1 gain <MAX=val> <MIN=val> <SCALE=val>
+ <TC1=val> <TC2=val> <M=val> <ABS=1> <IC=val>

Polynomial 

Fxxx n+ n- <CCCS> POLY(ndim) vn1 <... vnndim> <MAX=val> <MIN=val>
+ <TC1=val> <TC2=val> <SCALE=vals> <M=val> <ABS=1> p0 <p1...>
+ <IC=vals>

Piecewise Linear 

Fxxx n+ n- <CCCS> PWL(1) vn1 <DELTA=val> <SCALE=val><TC1=val>
+ <TC2=val> <M=val> x1,y1 ... x100,y100 <IC=val>

Multi-Input Gates

Fxxx n+ n- <CCCS> gatetype(k) vn1, ... vnk <DELTA=val> <SCALE=val>
+ <TC1=val> <TC2=val> <M=val> <ABS=1> x1,y1 ... x100,y100 <IC=val>

Delay Element

Fxxx n+ n- <CCCS> DELAY vn1 TD=val <SCALE=val> <TC1=val><TC2=val>
+ NPDELAY=val

F Element Parameters

ABS Output is absolute value if ABS=1.

CCCS Keyword for current controlled current source. CCCS is a Star-Hspice keyword and should not be used as a node name

DELAY Keyword for the delay element. The delay element is the same as a current controlled current source except it is associated by a propagation delay TD.This element facilitates the adjustment of propagation delay in the subcircuit model process. DELAY is a Star-Hspice keyword and should not be used as a node name.

DELTA Used to control the curvature of the piecewise linear corners. Defaults to 1/4 of the smallest of the distances between breakpoints. The maximum is 1/2 of the smallest of the distances between breakpoints.

Fxxx Current controlled current source element name. Must begin with "F", which may be followed by up to 15 alphanumeric characters.

gain Current gain.

gatetype(k) May be AND, NAND, OR, or NOR. The value of k is the number of inputs of the gate. The x and y terms represent the piecewise linear variation of output as a function of input. In the multi-input gates only one input determines the state of the output. The above keywords should not be used as node names.

IC Initial condition: the initial estimate of the value(s) of the controlling current(s) in amps. Default=0.0.

M Number of replications of the element in parallel.

MAX Maximum output current value. The default is undefined, and sets no maximum value.

MIN Minimum output current value. The default is undefined, and sets no minimum value.

n+/- Positive or negative controlled source connecting nodes.

NPDELAY Sets the number of data points to be used in delay simulations. The default value is the larger of 10 or the smaller of TD/tstep and tstop/tstep. That is,

The values of tstep and tstop are specified in the .TRAN statement.

p0, p1 ... The polynomial coefficients. When one coefficient is specified, Star-Hspice assumes it to be p1, with p0=0.0, and the element is linear. When more than one polynomial coefficient is specified by p0, p1, p2, ..., the element is nonlinear. See Polynomial Functions.

POLY Polynomial dimension. If POLY(ndim) is not specified, a one-dimensional polynomial is assumed. Ndim must be a positive number.

PWL Piecewise linear function keyword.

SCALE Element value multiplier.

TC1, TC2 First and second order temperature coefficients. The SCALE is updated by temperature:

TD Time delay keyword.

vn1... Names of voltage sources through which the controlling current flows. One name must be specified for each dimension.

x1,... Controlling current through vn1 source. The x values must be in increasing order.

y1,.. . Corresponding output current values of x.

Example

$ Current controlled current sources - F Elements, 

F1 13 5 VSENS MAX=+3 MIN=-3 5

F2 12 10 POLY VCC 1MA 1.3M

Fd 1 0 DELAY vin TD=7ns SCALE=5

Filim 0 out PWL(1) vsrc -1a,-1a 1a,1a

The first example describes a current controlled current source connected between nodes 13 and 5. The current that controls the value of the controlled source flows through the voltage source named VSENS (to use a current controlled current source, a dummy independent voltage source is often placed into the path of the controlling current). The defining equation is:

The current gain is 5, the maximum current flow through F1 is 3 A, and the minimum current flow is -3 A. If I(VSENS) = 2 A, I(F1) would be set to 3 amps and not 10 amps as would be suggested by the equation. A user-defined parameter may be specified for the polynomial coefficient(s), as shown below.

.PARAM VU = 5

F1 13 5 VSENS MAX=+3 MIN=-3 VU

The second example describes a current controlled current source with the value:

I(F2)=1e-3 + 1.3e-3 ·I(VCC)

Current flow is from the positive node through the source to the negative node. The direction of positive controlling current flow is from the positive node through the source to the negative node of vnam (linear), or to the negative node of each voltage source (nonlinear).

The third example is a delayed current controlled current source.

The fourth example is a piecewise linear current controlled current source.